Energy sector focusses to be able to meet all the requirements of sustainable national development of energy resources and efficient utilization of its diverse sources. Waste-to-energy technologies consist of various methods for extracting energy from waste materials. These methods include thermo-chemical processes such as combustion, gasification, and pyrolysis. These thermo chemical processes are highly endothermic in nature and have high energy consumption.  Fluidised bed exchangers play an important role in the “clean wastes technology” because of its high thermal efficiency, better scalability, better temperature control and high heat transfer surface area. The current project work focusses on understanding the impact of different tube configurations (size and numbers) on the fluidisation behaviour, along with heat transfer mechanisms. Computational fluid dynamics (CFD) modelling-based approach will be used to evaluate the hydrodynamics of the above system.  The results from this study, will be used to develop and establish correlations between tube size, shape, gas flow rates, and particle heat transfer mechanisms.

PhD Thesis underway by Shivani Agnihotri.

Conventional activated sludge (CAS) has been widely used for biological nutrient removal in the secondary treatment stage of the wastewater process for well over 100 years. Until recently, this technology has remained relatively unchanged until the emergence of aerobic granular sludge (AGS). This new technology has been identified as a potential replacement to the traditional microbial floc. AGS results in the biomass forming dense microbial granules with greater settling velocity, this can allow for greater volumes of wastewater to be treated by reducing the cycle times. This project will investigate several facets of the process  including impacts on water recycling (pathogen removal and tertiary disinfection), energy use or greenhouse gas emissions.

PhD Thesis completed by Benjamin John Thwaites in February 2021.

This project addressed major knowledge gaps regarding biological dynamics and solids behaviour in Als which lead to development of improved operating protocols, designed for efficient, stable and low-risk operation over the long term. Guidelines contributed to  low-cost treatment for domestic and industrial wastewaters whilst enabling recovery of renewable energy to further offset treatment costs.   A novel pilot-scale anaerobic lagoon reactor with sufficient height to replicate sludge and scum stratification that occurs in full-scale ALs was designed, built and commissioned to achieve these results.

PhD Thesis completed by Peter Wardop in 2021.

The steam produced by boiling a kettle of salty water can be collected, condensed and drunk. Membrane distillation is an analogous process to this, but in this study the salty feedwater forms a salt-free vapour at a lower temperature; 30 – 40°C. The warm feedwater and vapour are pumped past a thin, porous membrane which repels liquid water but allows vapour to pass through the pores into a cold stream of freshwater on the other side. The vapour condenses and increases the volume of fresh, salt-free water. In this project an operational pilot plant was built and installed at an electricity generating station which produces waste heat and a stream of salty effluent that is normally discarded. The pilot plant was equipped with a 0.67m2 membrane, ran continuously for 3 months, and produced an average of 2.2L freshwater per hour. This equates to 3.4L/h/m2. The membrane area can be scaled up to increase production. It was concluded that this is a viable treatment technology for industrial wastewater that emits minimal greenhouse gasses.

Water utilities lack the information they need to implement risk-based adaptation and planning strategies that incorporate climate change. This research addresses this problem by modelling the effects of climate change on reservoirs in three climate zones: temperate, humid tropical and Mediterranean. By integrating different modelling approaches it was concluded that increased temperatures will increase water stratification; the differences in water temperature that occur with depth. This is important because the duration and type of stratification affects the storage and release of substances from reservoir floors and this in turn affects blue-green algal blooms and water quality. The integrated modelling approach developed in this project can be applied to the management of contaminants running off the catchments and for future risk assessment. This information will also support the development of business cases for targeted catchment interventions.

The protection of sources of water and catchments is an important method for maintaining water quality; one that can mitigate cost and reliance on downstream water treatment and disinfection. Catchment protection requires risk assessment, but water quality management approaches were not originally developed for natural environments, and ecosystem-based methods (such as the Ecological Risk Assessment methodology), require complex data inputs often unavailable to water utilities.

This paper discusses various water quality risk management techniques and proposes a step-by-step catchment risk assessment methodology that is compatible with the Australian Drinking Water Guidelines.